DESCRIPTION This project will test the hypothesis that exposure to radiation exacerbates the diet-induced atherosclerosis by increasing the expression of adhesion factors and enhancing the retention of LDL by the artery. The applicant will measure the accumulation of labeled LDL in mouse arteries following radiation treatment. She will study the effect of radiation on the arterial expression of various adhesion molecules by using immunoflourescent methods. The possible role of superoxide in the above processes will be tested by determining whether the effects are less pronounced in transgenic mice over-expressing SOD. The results will not only help explain the acceleration of atherosclerosis by therapeutic radiation, but also provide information on the basic mechanisms of atherosclerosis.